Similar to base jumping, but instead of freefalling, the diver is equipped with flaps below their arms and between their legs. The diver then "flies" around similar to a flying squirrel. Most wingsuit jumpers attempt to fly as close to the cliff/wall as possible.
Guy 1 - Hey, we're going to the Alps to go wingsuit (base) jumping... you wanna come?
Guy 2 - Hell ya, we'll be flying like sqirrels!